P0606 is a generic powertrain code indicating that the Powertrain Control Module (PCM) or Engine Control Module (ECM) has detected an internal processor malfunction. The module's central processing unit has failed its self-test or encountered an internal fault that prevents normal operation.
Low battery voltage or erratic charging can corrupt the PCM's processor memory or cause voltage spikes that damage internal circuits.
Corroded, loose, or damaged power/ground connections to the PCM can cause voltage fluctuations that trigger processor errors.
Shorts, opens, or chafed wires in the PCM wiring harness can introduce electrical noise or intermittent power loss.
Performance chips, programmers, or unauthorized software modifications can conflict with the PCM's internal processes.
Jump-starts, electrical shorts, or voltage spikes from other components can temporarily or permanently damage the processor.
True internal PCM failure is rare and should only be diagnosed after all other electrical causes are ruled out.
The definition is universal; the diagnostics are engine-specific. Open your vehicle for the codes documented for it:
No. While the code indicates a processor fault within the PCM, the actual cause is rarely the module itself. Most P0606 codes are caused by electrical supply problems—weak battery, bad grounds, corroded connectors, or wiring issues. The PCM is replaced only after all power and ground diagnostics are completed with no faults found.
It depends on severity. Some vehicles will run in limp mode with reduced power, while others may not start or may stall unexpectedly. Driving is not recommended until the issue is diagnosed, as a failed PCM processor can cause unpredictable engine behavior.
No. Clearing the code will not fix an actual processor fault. If the underlying electrical issue (low voltage, poor connections) is not addressed, the code will return, potentially even faster due to the PCM being more sensitive after a reset.
Replacement costs vary significantly by vehicle make and model. A new OEM PCM often requires programming by a dealer or qualified shop, which adds labor costs. However, replacement should only be considered after confirming all power, ground, and wiring issues are not the cause.